Hi,
Yep, you can build a touch screen application with either technology, although web based is more difficult to design and build than windows based.
You have to decide whether the benefits of a web based application outweigh the added effortin writing and reduced functionality compared with a windows application.
As far as benefits to base that on? Here are a few comments on that...
Web based application is a centralised application and means simpler upgrades and management in general. It also means nothing to manually download to the client so potentially a simpler "distribution" for the software. It enables access to your application for anywhere, anytime (if on the net)
It suffers from browser incompatibilities and reduced functionality as compared to windows applications. Also can be significantly slower. Increased complexity comes from the "statelessness" of the net.
I'm sure you can think of other reasons both for and against your application being a web application. Think them all through, and make your decision based on that...
Hope I've helped,
Cheers,
Tim.